Nervous System - Introduction Flashcards
What are the two Anatomical Classifications for the Nervous System?
- Central Nervous System (CNS)
- Peripheral Nervous System (PNS)
What is the function of the CNS? what parts of the human body contribute to the CNS?
Function - Processing Information - Analyzing Infromation - Generating appropriate motor responses Components - Brain - Spinal Cord
From an embryological perspective, what three parts make up the brain?
- Forebrain
- Midbrain
- Hindbrain
What is the Function of the PNS? What are the components of the PNS?
Function - Collecting sensory information - Distributing Motor output from CNS Components - Cranial Nerves (12 Pairs) - Spinal Nerves (31 pairs) - Peripheral Ganglia: a group of cells outside of the CNS
From a Functional Perspective, what are the Three Components of the Nervous System?
- Somatic
- Visceral
- Enteric
What is the Enteric Nervous System?
- Large Division of PNS
- Controls the Gastrointestinal Behaviour Independently
- Contains the Enteric Plexus
What is the Enteric Plexus?
- Complex autonomic nerve plexus
- Inside walls of the Gastrointestinal Tract
- Contains intrinsic sensory and motor axons connected through local ganglionic interneurons
What is the overall function of the PNS?
- Collect sensory information
- Distribute motor output
What are the Main Sources of Sensory Information? (3)
- Somatic: from the external environment such as pain and temperature
- Special Sense: Fearing, Vision, Balance
- Visceral Senses: From internal Organs
What are the main Motor Outputs of the PNS? examples?
- Somatic Nerves: muscles
- Autonomic Motor Outputs: Cardiac muscles, digestive system, glands
What are the three parts of the Autonomic Motor System?
- Sympathetic Part
- Parasympathetic Part
- Enteric Plexuses
At 3-4 weeks of embryonic development: Describe the CNS
- Hollow Cylinder with Three Vesicles
What are the names of the 3 primary cerebral vesicles present at 3-4 weeks of embryonic development?
- Prosencephalon
- Mesencephalon
- Rhombencephalon
At 5 weeks of embryonic development: describe the CNS
- Secondary Cerebral Vesicles: 5 of them
What are the 5 Secondary Cerebral Vesicles of the CNS at 5 weeks of embryonic development?
- Telencephalon
- Diencephalon
- Mesencephalon
- Metencephalon
- Myelencephalon
What does the Telencephalon turn into?
- Cerebrum
What does the Diencephalon turn into? (3)
- Thalamus
- Hypothalamus
- Epithalamus
What does the Mesencephalon turn into? (1)
- Midbrain
What does Metencephalon turn into? (2)
- Pons
- Cerebellum
What does the Myelencephalon turn into? (1)
- Medulla Oblongata
Where does the Spinal Cord form?
- From the distal part of the hollow cylinder of 3 vesicles at 3-4 weeks of embryonic development
- The Midbrain, pons, and medulla oblongata
What are the structure and average length of the spinal cord?
Structure
- Cylindrical
Length
- 43-45cm
Where does the spinal cord start and end?
Starts
- At the base of the skull and the CI vertebra
Ends
- In 70% of people it ends at the LI - LII vertebra
- in taller people could end at TXII and in Shorter person at around LIII
What is the name of the caudal end of the Spinal Cord?
- Conus Medularis
Where are the 2 enlargements on the Spinal Cord? Why are they there?
Location - Cervical Enlargement - Lumbar Enlargement Function - Spinal Nerves arise to form Brachial Plexus and Lumbar Plexus for upper and lower limbs
What are Spinal Segments?
- section of the spinal cord that gives rise to one pair of spinal nerves
What are the differences in vertebra level and spinal segment level at different sections of the vertebral column? (4)
- Cervical Vertebra: SS is 1 lower than VL
- Upper Thoracic: 2 lower
- Lower Thoracic: 2 lower
- Lumbar Vertebrae: 5 lower
What components make up a Cross-section of a spinal segment? (2)
- Gray Matter
- White Matter
What is Grey Matter composed of?
- Nerve cell bodies
- unmyelinated fibers
- supporting cells
What is White Matter composed of?
- Myelinated Fibers
What is the structure of Gray Matter in a Cross-Section of a Spinal Segment?
- Resembles Butterfly
- Has 2 or 3 horns depending on segment
What are the 3 different types of horns in Grey Matter in the Spinal Cord? What sections have 3 horns and what have 2?
Horns - Posterior (dorsal) horn - Anterior (ventral) horn - Lateral horn 2 or 3 Horns - Segments C1-C8: 2 Horns - Segments T1-L2: 3 Horns - Segments L3-S1: 2 Horns - Segments S2-S4: 3 Horns - Segments S5-Co: 2 Horns
What is the Lateral Horn of Gray Matter in the Spinal Cord?
- 3rd Horn
- Only present in some sections
- Autonomic Neurons for para/sympathetic responses
What are the 2 sections of the spinal cord that have 3 horns in the gray matter? What neurons does each section have?
Sections - T1-L2 - S2-S4 Neurons - T1-L2: Sympathetic - S2-S4: Parasympathetic
Make-up, Function, and Location of Nerve Tracts?
Tracts
- Myelinated Fibers
Function
- Send sensory information towards the brain
- Send motor information away from the brain
Location
- In the White Matter of the Spinal Cord
What are the Three Columns of White Matter in the Spinal Cord?
- Posterior (dorsal) column
- Lateral Colum
- Anterior (ventral) Column
What is the Ventral Root comprised of?
- Pure Motor fibers/rootlets exiting the spinal cord
What is the Dorsal Root Comprised of?
- Pure Sensory fibers/rootlets entering the spinal cord
What is the Dorsal Root Ganglion (DRG)?
- A ganglion of dorsal root composed of sensory nerve cell bodies
What is the difference between a cluster of nerve cell bodies inside or outside the CNS?
- Inside: A Nuclei
- Outside: A Ganglion
What is a Spinal Nerve?
- Joining of Dorsal and Ventral Roots
- Two pairs at each spinal cord segment
